5 March 2024
The paper describes a family of novel bio- and CO2-based poly(isosorbide-co-diol) oxalate (PISOX-diol) copolyesters that are not only fully renewable but also show very promising environmental degradation characteristics. It describes how tuning the composition of the copolyesters can target a broad range of applications – from the polymer coating of controlled-release fertilizers to film applications as well as rigids for packaging, 3D printing and many other purposes. The paper provides a strategy for optimizing the resulting properties (thermal, mechanical, barrier, hydrolysis, and biodegradation) with respect to the intended applications.
To reduce the global CO2 footprint of plastics, bio- and CO2-based feedstock are considered the most important design features for plastics. Oxalic acid from CO2 and isosorbide from biomass are interesting rigid building blocks for high Tg polyesters. The biodegradability of a family of novel fully renewable (bio- and CO2-based) poly(isosorbide-co-diol) oxalate (PISOX-diol) copolyesters was studied. We systematically investigated the effects of the composition on biodegradation at ambient temperature in soil for PISOX (co)polyesters. Results show that the lag phase of PISOX (co)polyester biodegradation varies from 0 to 7 weeks. All (co)polyesters undergo over 80% mineralization within 180 days (faster than the cellulose reference) except one composition with the cyclic co-diol 1,4-cyclohexanedimethanol (CHDM). Their relatively fast degradability is independent of the type of noncyclic co-diol and results from facile nonenzymatic hydrolysis of oxalate ester bonds (especially oxalate isosorbide bonds), which mostly hydrolyzed completely within 180 days. On the other hand, partially replacing oxalate with terephthalate units enhances the polymer’s resistance to hydrolysis and its biodegradability in soil. Our study demonstrates the potential for tuning PISOX copolyester structures to design biodegradable plastics with improved thermal, mechanical, and barrier properties.
Yue Wang, Kevin van der Maas, Daniel H. Weinland, Dio Trijnes, Robert-Jan van Putten, Albert Tietema, John R. Parsons, Eva de Rijke, and Gert-Jan M. Gruter: Relationship between Composition and Environmental Degradation of Poly(isosorbide-co-diol oxalate) (PISOX) Copolyesters. Environ. Sci. Technol. 2024, 58, 5, 2293–2302. Publication Date: January 26, 2024. DOI: 10.1021/acs.est.2c09699